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When two cars with different masses collide head-on, which car experiences a greater change in momentum?
- A. The car with the larger mass
- B. The car with the smaller mass
- C. Both cars experience the same change in momentum
- D. It depends on the initial velocities of the cars
Correct Answer: C
Rationale: In a head-on collision between two cars, the law of conservation of momentum states that the total momentum of the isolated system remains constant before and after the collision. The change in momentum of one car is equal in magnitude but opposite in direction to the change in momentum of the other car. As a result, both cars experience the same change in momentum during the collision. Choice A is incorrect because the change in momentum is the same for both cars due to the conservation of momentum principle. Choice B is incorrect as the smaller mass car does not experience a greater change in momentum. Choice D is incorrect as the initial velocities of the cars do not determine which car experiences a greater change in momentum; it is solely dependent on the masses of the colliding cars.
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What does the term 'colligative property' refer to in solutions?
- A. Properties that depend on the nature of the solute particles
- B. Properties that depend on the concentration of solute particles
- C. Properties that depend on the temperature of the solution
- D. Properties that depend on the pressure of the solution
Correct Answer: B
Rationale: Colligative properties are properties of a solution that depend on the concentration of solute particles, regardless of the identity of the solute. These properties include lowering the vapor pressure, elevation of boiling point, depression of freezing point, and osmotic pressure. The concentration of solute particles affects these properties, not the nature, temperature, or pressure of the solution. Therefore, choice B is the correct answer as it accurately reflects the definition of colligative properties. Choices A, C, and D are incorrect because colligative properties are not based on the nature, temperature, or pressure of the solute, but rather on the concentration of solute particles in the solution.
Homologous structures are similar structures in different organisms that have a common evolutionary origin. An example is:
- A. Butterfly wings and bird wings (analogous structures with different origins)
- B. The arm of a human, the wing of a bat, and the flipper of a whale
- C. The eyes of an octopus and a human (convergent evolution with different origins)
- D. The stinger of a bee and the barb of a cactus (unrelated structures)
Correct Answer: B
Rationale: Homologous structures are similar structures found in different organisms that share a common evolutionary origin. The arm of a human, the wing of a bat, and the flipper of a whale are all examples of homologous structures. Despite serving different functions, they share a common underlying structure due to their evolutionary relationship, evidencing a shared ancestry. These structures are modified over time to suit the specific needs of each species. Option A (Butterfly wings and bird wings) refers to analogous structures with different origins. Option C (The eyes of an octopus and a human) describes convergent evolution where traits evolve independently. Option D (The stinger of a bee and the barb of a cactus) are unrelated structures.
What is the main difference between a nuclear reactor and a nuclear bomb?
- A. Reactors use enriched uranium, while bombs use natural uranium.
- B. Reactors have controlled chain reactions, while bombs have uncontrolled chain reactions.
- C. Reactors generate electricity, while bombs cause explosions.
- D. Reactors use moderators, while bombs don't.
Correct Answer: B
Rationale: The main difference between a nuclear reactor and a nuclear bomb is that reactors have controlled chain reactions, while bombs have uncontrolled chain reactions. Nuclear reactors are designed to sustain a controlled nuclear reaction to generate electricity. In contrast, nuclear bombs are designed to release a massive amount of energy in an uncontrolled chain reaction, resulting in an explosion. Choice A is incorrect because both reactors and bombs can use enriched uranium. Choice C is incorrect as nuclear reactors also generate electricity, not just bombs. Choice D is incorrect because both reactors and bombs may or may not use moderators, but the key distinction lies in the control of the chain reaction.
Imagine you have an element with atomic number 20 and mass number 40. How many neutrons does it have?
- A. 20
- B. 40
- C. 10
- D. 20
Correct Answer: C
Rationale: - The atomic number (Z) represents the number of protons in an atom. In this case, the atomic number is 20.
- The mass number (A) represents the total number of protons and neutrons in an atom. In this case, the mass number is 40.
- To find the number of neutrons, you subtract the atomic number from the mass number: Neutrons = Mass number - Atomic number.
- Neutrons = 40 - 20 = 20.
- Therefore, the element with atomic number 20 and mass number 40 has 20 neutrons.
Which of the following terms refers to a muscle twitch, a single forceful contraction of a muscle fiber?
- A. Tetanus
- B. Tremor
- C. Fasciculation
- D. Rigidity
Correct Answer: C
Rationale: The correct term for a muscle twitch, a single forceful contraction of a muscle fiber, is 'Fasciculation' (choice C). Fasciculation specifically describes this phenomenon. 'Tetanus' (choice A) refers to sustained muscle contraction, 'Tremor' (choice B) indicates a shaky or quivering movement, and 'Rigidity' (choice D) denotes stiffness or inflexibility in muscles. Therefore, choices A, B, and D are incorrect in the context of a single forceful contraction of a muscle fiber.